1. Field of the Invention
This invention relates to a photosensitive member for electrophotography, and particularly to a photosensitive member for electrophotography with a photosensitive layer containing a specific azo pigment.
2. Related Background Art
Photosensitive members for electrophotography utilizing inorganic photoconductive substances such as selenium, cadmium sulfide, zince oxide, etc. as a photoconductive component have been so far well known. On the other hand, since specific photoconductive organic compounds were found, many organic photoconductive substances have been developed. For example, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, etc.; low molecular weight organic photoconductive compounds such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, polyarylalkanes, etc.; and organic pigments and dyes such as phthalocyanine pigment, azo pigment, cyanine pigment, polycyclic quinone pigment, perylene-based pigment, indigo dye, thio indigo dye, and squarilium dyes, etc. are known. Particularly, the photoconductive organic pigments and dyes can be more readily synthesized than the inorganic substances, and have variations in selecting a suitable compound showing a photoconductivity for a desired wavelength range. Thus, many photoconductive organic pigments and dyes have been proposed. For example, photosensitive members for electrophotography utilizing a photoconductive disazo pigment as a charge-generating material in a photosensitive layer having a charge generation layer and a charge transport layer as functionally separated are known, as disclosed in U.S. Pat. Nos. 4,123,270; 4,247,614; 4,251,613; 4,251,614; 4,256,821; 4,260,672; 4,268,596; 4,278,747; 4,293,628, etc.
The photosensitive members for electrophotography utilizing such organic photoconductive compounds can be produced by coating when an appropriate binder is selected, that is, can be produced with a very high productivity at a low cost, and also have such an advantage that the photosensitive wavelength range can be controlled as desired by selecting an appropriate organic pigment. However, these photosensitive members have poor sensitivity and durability and thus only a few of them have been practically utilized.